The impact of time varying equilibrium location in the semi-active control of non-linear seismically excited structures

A main goal of supplemental control devices is to manage the energy dissipation in the system. Semi-active damping devices have emerged as a promising control device for application to civil structures as they are effective energy dissipators. The inclusion of structural non-linearities in control assessment simulations presents new challenges that must be considered in the application of semi-active control systems. This paper presents a semi-active control utilizing semi-active devices and investigates its ability to mitigate structural response in the presence of hysteretic, geometric and yielding non-linearities under various intensity level seismic hazard suites so as to examine control efficacy and seismic hazard statistics. Due to the non-linear models used, the permanent deformations that result from large excitations result in a time-varying equilibrium position. Hence, a key feature of this research is the inclusion of a moving-zero within the control law, effectively tracking the permanently deformed position about which the structure oscillates, and its impact on control efficacy.